A new paper in GRL published Sep 6th Secular temperature trends for the southern Rocky Mountains over the last five centuries makes use of some tree core sample data gathered by Steve McIntyre and Mr. Pete. Readers of WUWT and Climate Audit may recall that in the summer of 2007, Steve left CA in my attendance for a couple of weeks while he went to Colorado to visit his sister, and to prove or disprove his ‘Starbucks hypothesis’ which asks:

…could a climate scientist have a Starbucks in the morning, collect tree rings through the day and still be home for dinner?

This came about because apparently RealClimateScientists™ don’t have the funds or time to get out of the office and gather new tree core samples, such as cores that would fill in the last 25 years that seems to be part of that “tricky” divergence problem. In A Little Secret (Oct 2007) Steve wrote:

Don’t you think that someone on the Team might have been a little curious as to what bristlecone ring widths have done during the past 25 years? For this, we have the classic excuse of Michael Mann and the Team for not updating bristlecone and proxy records is that it’s not practical within the limited climate budgets:

While paleoclimatologists are attempting to update many important proxy records to the present, this is a costly, and labor-intensive activity, often requiring expensive field campaigns that involve traveling with heavy equipment to difficult-to-reach locations (such as high-elevation or remote polar sites). For historical reasons, many of the important records were obtained in the 1970s and 1980s and have yet to be updated.

This new paper proves that you can do field science on vacation, while visiting Starbucks, and in a single day. It also has a thing or two to tell us about the accuracy of tree ring width and wood density records and their value as a temperature proxy.

First, the calibration of the d18Oc data with instrumental temperature data from the nearby Cheesman USHCN station.

Figure 1A. Timeseries of temperature anomalies reconstructed from d18Oc and that observed at the Cheesman meteorological station. Error bars represent the uncertainty in the temperature timeseries that arises both from the spread of tree-to-tree values and the uncertainty in the slope of the transfer function.

Abstract:

Pre-instrumental surface temperature variability in the Southwestern United States has traditionally been reconstructed using variations in the annual ring widths of high altitude trees that live near a growth-limiting isotherm. A number of studies have suggested that the response of some trees to temperature variations is non-stationary, warranting the development of alternative approaches towards reconstructing past regional temperature variability. Here we present a five-century temperature reconstruction for a high altitude site in the Rocky Mountains derived from the oxygen isotopic composition of cellulose (d18Oc) from Bristlecone Pine trees. The record is independent of the co-located growth-based reconstruction while providing the same temporal resolution and absolute age constraints. The empirical correlation between d18Oc and instrumental temperatures is used to produce a temperature transfer function. A forward-model for cellulose isotope variations, driven by meteorological data and output from an isotope-enabled General Circulation Model, is used to evaluate the processes that propagate the temperature signal to the proxy. The cellulose record documents persistent multidecadal variations in d18Oc that are attributable to temperature shifts on the order of 1C but no sustained monotonic rise in temperature or a step-like increase since the late 19th century. The isotope-based temperature history is consistent with both regional wood density-based temperature estimates and some sparse early instrumental records.

Figure 3. (top) Reconstructed (JJA) max. temperature anomalies based on the d18Oc from two long cores (blue and green) at the Almagre Mt. site. The mean of the reconstruction was smoothed with a 20-year bandpass filter (black) to accentuate low frequency trends. (top middle) Reconstructed AMJJAS max. temperatures for the same site based on variations in annual growth [LaMarche and Stockton, 1974]. (bottom middle) Reconstructed AMJJAS max. temperatures for the region based on variations in wood density variations [Briffa et al., 1992]. (bottom) Difference between the temperatures reconstructed from d18Oc and ring width variations (purple) and the difference between temperatures reconstructed from wood density [Briffa et al., 1992] and ring width variations (green).

Discussion

During the 20th century, the summer surface temperatures in this region are characterized by a broadly parabolic trend, with minima during the 1930s and early 1980s
and a period of relative warmth during the late 1940s to early 1960s (Figure 1). The temperature reconstruction based on d18Oc suggests that in terms of mean temperature and multidecadal variance, the 20th century is largely comparable to
the preceding 4 centuries (Figure 3).

Despite the seemingly good correspondence between tree ring width (Figures 3 and S5) and d18Oc proxies during the instrumental period, over much of the previous 400 years
the two records exhibit very different climate histories (Figure 3). Prior to the mid 19th century the width-based reconstruction indicates temperatures at this site were
approximately 0.7C cooler than during the instrumental era while the d18Oc reconstruction suggests that temperatures have remained stable. The residual between these two reconstructions (Figure 3) is sufficiently large and sustained to suggest the existence of a significant bias in one or both of these two proxies that cannot likely be explained as arising simply from random errors in the linear transfer function.
Daux et al. [2011] also note an apparent divergence between width and isotope based temperature reconstructions in Larix decidua from France. They attribute the divergence
possibly to changes in the soil hydrology (i.e., plant utilization of soil water enriched by evaporation) or moisture stress. At this site, soils are thin and the trees are characteristically shallow-rooted and it is thus unlikely that deeper, low-residence time water would be available. Further no indication of anomalous 20th water stress or abundance is seen in either d13C from pinyon pine trees across the region [Leavitt et al., 2007] or widths from lower elevation drought-stressed trees [Cook et al., 1999].

To help resolve this enigma, an additional temperature proxy that is based on a regional composite of wood density measurements is considered [Briffa et al., 1992] (Figures 3 and S5). This temperature proxy is independent of both tree growth rate and the isotopic composition of cellulose and is shown to have high skill as a growing season temperature proxy in this region (Figure S5). To test the consistency between density and isotope-derived temperatures we look at the cross-wavelet [Grinsted et al., 2004] between the records (Figure S6). In the multi-decadal window, the density and isotope reconstructions are consistently in-phase with one another through the last 400 years, implying that the two proxies are likely being influenced by a common climate parameter, which we assume to be growing season surface temperature variations. With respect to the cross-wavelet between widths and isotopes, the two appear to only be commonly forced during the 20th century (Figure S6).

Further confirmation of this is garnered by looking at early instrumental data from the region (not shown), which indicate that surface temperatures between 1850–1870 were, on average, as warm as those of the 1930s–1960s [Wahl and Lawson, 1970], which is consistent with the relative thermal stability implied by the isotopic and
density reconstructions. Taken together, the d18Oc and wood density records provide a fairly consistent perspective on multidecadal temperature variations, which suggest a coolbias in the width-based temperatures prior to the mid 19th century.

Conclusions
The isotope temperature record from this site indicates relatively stable summer season temperatures amidst decadal to multidecadal temperature fluctuations. Although
the isotope reconstruction is associated with several significant sources of uncertainty that arise from the transfer function and tree-to-tree heterogeneity, the results highlight the need for, 1) additional efforts to extend a processbased network of temperature reconstructions across the region and 2) develop pre-instrumental forward model simulations (for both widths and isotopes) that could be used to test the assumptions of linearity that underlie the proxy reconstructions.

The main points of the paper are:

Temp. trends in the SW US can be reconstructed using isotopes in tree rings

A process model of the proxy can be used to characterize uncertainty in proxy

Temperature trends in SW US have been relatively stable over last 5 centuries

Acknowledgments. The authors thank M. Zhu, G. Kleber and
M. Rincon for invaluable assistance in sample preparation and analysis;
Z. Gedalof and J. Franks for cross dating the samples used in this analysis;
V. Bommarito, L. Holzmann, P. Holzmann, R. Lee, N. McIntyre S. McIntyre, L. Thomas for sample collection; A. Ballantyne for feedback
on an earlier version of the paper; K. Yoshimura for providing outputs
from the IsoGSM simulations; 2 anonymous reviewers for suggestions
on improving the manuscript and the ITRDB for tree ring data. Funding
was provided by NOAA Award NA10OAR4310129 to LDS.

This effort, peer reviewed paper, and results just goes to show that citizen science can do what RealClimateScientists™ can’t or won’t, and do it just as effectively. For those who worry about such things, it should be noted that Steve applied for, and got permission for the core sampling of the Bristlecone pines in Colorado.

…expensive field campaigns that involve traveling with heavy equipment to difficult-to-reach locations (such as high-elevation or remote polar sites).

Reminds me of that Dr Seuss book “Scrambled Eggs Super” where the kid fantasizes about collecting all kinds of exotic eggs from around the world. If memory serves it did include high-elevations and remote polar sites.

How long is the growing season at that altitude? I always thought this proxie might be good for summer temperatures (in Colorado,) but left a total blank in terms of fall-winter-spring temperatures.

Another question people wondered about back in 2007 was whether or not higher levels of CO2 might make these trees grow a little faster. In which case increased recent growth would hide cooling, and make cooling look like warming. Has this issue been discussed?

“With respect to the cross-wavelet between widths and isotopes, the two appear to only be commonly forced during the 20th century (Figure S6).”

So here instead of a divergence problem we have convergence.

Lots of lines of evidence (although not warming) point to a 20th century game change. Human CO2 may be doing other stuff, like removing a constraint on photosynthesis. I’d love to see the 13C profiles of those rings.

One question about the Cheesman USHCN station. How well situated is the site considered?
From the image here: http://gallery.surfacestations.org/main.php?g2_itemId=50424
It looks like a typical mountain setting with a low tree density.
However, it is less than nine meters from a large concrete pad, a maintenance building, and in between two dirt roads.

You have to remember it takes a lot more work to find those special trees like YAD061. You never know when any particular tree might be skeptically inclined or paid to grow by fossil fuel companies. ;)

…expensive field campaigns that involve traveling with heavy equipment to difficult-to-reach locations (such as high-elevation or remote polar sites).

I do feel for these poorly funded calamatologists.

November 21, 2002
Four big international companies, including the oil giant Exxon Mobil, said yesterday that they would give Stanford University $225 million over 10 years for research on ways to meet growing energy needs without worsening global warming.

I would think that tree ring size would be more closely related to the length of the growing season than the temperature. That might mean the same thing in terms of average summer temperature, but it makes a big difference for inhabitants.

“While paleoclimatologists are attempting to update many important proxy records to the present, this is a costly, and labor-intensive activity…”

Yeah, those Starbucks lattes would have cost Mike a lot of bucks.

“…often requiring expensive field campaigns…”

Campaigns? This isn’t exactly D-Day, Mike.

“…that involve traveling with heavy equipment…”

Like an auger, a coring bit, and Michael Mann’s hat.

“…to difficult-to-reach locations (such as high-elevation or remote polar sites). For historical reasons, many of the important records were obtained in the 1970s and 1980s and have yet to be updated.”

Historical reasons: a scientist’s place in history depends on nobody getting newer data. /sarc

I always thought that the most likely correlation would be between amount of snowpack and treering width, observing that apart from snowmelt, those trees get precious little water in the form of precipitation

Jimmy Haigh says:
September 11, 2012 at 9:41 amBut why? Was there no Little Ice Age? Or is it because trees are just not good thermometers?
Several possibilities:
1) perhaps LIA was not global
2) perhaps trees no good for temperatures
3) perhaps solar activity was not a low as thought
Pick your poison.

“Tree rings generally grow wider during warm periods and narrower during cold ones”. It seems that tree rings would grow wider during wet years and narrower during dry years. As a lay person not schooled in dendrochronology, how do you tell the difference? Seems like tree rings could tell you 30″/yr vs 10″/yr of rain. How does this work for temperature?

I planted about a dozen saplings in my yard in 2000, most are about the same size now, but the largest is 20 feet away from the smallest which is about 60-70% of the size of the larger one. I can explain why they are different, but if the wood was harvested in 50-100 years no one else would be able to.

Re: Leif, “Pick your poison”
4) Perhaps the desert southwest is more in tune with the ENSO/SST induced rainfall patterns, and didn’t experience the pattern shifts of the Arctic circumpolar vortex during the LIA and Dalton.

There’s another possibility Leif.
4) That even though the LIA was global it wasn’t evenly distributed throughout all locales, in other words, some places wouldn’t have had a temperature drop even if most places did.http://www.co2science.org/data/mwp/qualitative.php

John W says:
September 11, 2012 at 10:05 amAre you saying that it did not happen?
Not necessarily, just introducing some caution in interpreting proxies. Of course, when the proxies confirm one’s pet theory they are good, right? And when not, they are bad [or other effects corrupt the data], right?

I now understand why the climate guys are moving to Colorado. It would seem from the graphs that this area is immune to any climate change! Guess this begs the question is the science really settled? Just another pin in the hat of the more we learn the less we really understand.

Don Keiller says:
September 11, 2012 at 10:13 amBut this work is only representative of one small location.
It cannot and does not have relevance/teleconnect to the global situation.
Yet people are falling all over each other to trumpet the relevance of this series. If it is not relevant, then why laud it?

“Not necessarily, just introducing some caution in interpreting proxies. Of course, when the proxies confirm one’s pet theory they are good, right? And when not, they are bad [or other effects corrupt the data], right?’

amen to that Leif. Sometimes proxies are an inkblot test.

Notice the following: X cannot warm the planet because lts cool here and there. Or one could say that X cannot cool the planet because its warm here or there. Same basic argumentative structure.
A lowering of solar activity cannot cool the planet, because during the LIA summers were just as hot. C02 cannot warm the planet because its cold in my neighborhood.

MiCro says:
September 11, 2012 at 9:58 am
“I planted about a dozen saplings in my yard in 2000, most are about the same size now, but the largest is 20 feet away from the smallest which is about 60-70% of the size of the larger one. I can explain why they are different, but if the wood was harvested in 50-100 years no one else would be able to.”

Agreed. When I purchased my house in 2001 there was a terribly neglected tangerine tree in the front yard. I have nursed it back to health, it has grown into a beautiful tree that produces lots of excellent fruit. If someone wanted to use that tree to support AGW they might have a very good proxy for their point of view but would not really know the reason why there was increased growth since 2001. Unless one knows the nutritional history of a tree, it doesn’t seem logical to use it solely for a temperature proxy.

The charting doesn’t go back far enough to tell us much of anything about the Maunder Minimum other than its tail end. The Dalton Minimum seems to have some presence, but the wood density suggests there would have been other confounding factos such as moisture and cloud cover which would tend to make the trees not so good as temperature recording instruments.

This is clearly all wrong. First of all, the deniers who wrote this are not members of the Climate Seance Club (TM). Secondly, they did not use the right trees, only certain magic trees work as proxies, and you have to be a member of the Climate Seance Club (TM) to get the secret decoder ring which allows one to pick the right trees. The PROPER research for a paper like this requires large amounts of money, and ours is all being spent on Climate Seance Communications to ensure the public is aware of the truthiness of Climate Seance. Clearly you have never been to a Climate Sceance or you would know all of this.

Steven Mosher says:
September 11, 2012 at 10:49 amA lowering of solar activity cannot cool the planet, because during the LIA summers were just as hot.

Yes and no.
I’ve been pointing that for some years now.http://www.vukcevic.talktalk.net/CETsw.htm
– Yes, because the TSI doesn’t vary much and the N. Hemisphere gets most of it in summer and least in the winter, and yes the winters are that have the 300 year uptrend.
– No, because temperature natural variability is caused by geomagnetic activity, which lasts longer during the night, and the winter nights are much longer than the summer nights.
See you. :)

So, you say collecting this kind of data is cheap. On the other hand, it does not support computational climate model ensemble projections. While running such models is extremely expensive, for they need supercomputers and development of several million lines of code.

Therefore cheap datasets like this are useless, they should be thrown out ASAP, on purely economic grounds. Let real scientist conduct their costly, labor-intensive activity instead, with expensive field campaigns that involve traveling with heavy equipment to difficult-to-reach locations (like Starbucks), until those few lucky trees are found, whose record is consistent with the models, that is, they lend support to science, amply demonstrating their worth.

We allocated some time from our Eastern Sierra Trout fishing expedition this past July, and spent a couple of hours at Sheep Mountain/Patriarch Grove. I managed to catalog about twenty tagged trees (one or two trees provided a bit of a mystery), but due to time constraints I couldn’t delve in to the Graybill Bristlecones. I plan on returning next year. This might be a bit more plausible than a Yamal expedition. The Sheep Mountain area is approx. 39 mile NE of Big Pine via highway 168, the last 20 miles or so being a steep and windy dirt road, but drivable. Anyone up for it?

Perhaps the Little Ice Age doesn’t show in the rings of these bristlecones, but, as I recall, it does show in the altitude the trees grow at. There are dead bristlecones still standing, at an altitude above this grove.

I’m not sure if they died at the close of the MWP, or some earlier climate optimum. However they are there.

Yes to a WUWT bristlecone expedition. Also an expedition following Hanibals route over the Alps which were less glaciated and more accessible in Roman times and yes to an expedition to Greenland. (not that you mentioned the last two of course)
tonyb

>>>RHS says:
September 11, 2012 at 9:05 am
One question about the Cheesman USHCN station. How well situated is the site considered?
From the image here: http://gallery.surfacestations.org/main.php?g2_itemId=50424
It looks like a typical mountain setting with a low tree density.
>>>It’s the best of the USHCN sites along the Front Range. Boulder’s site has a checkered siting history, and Fort Collins was set up on a farm plot which now harbors a bus station within the city.
Cheesman itself isn’t the best rural site – note that it’s right next to the reservoir, with variable distance from the water line.
It’s good that the data analysis ends around 2002, which was the year of a traumatic event for that area – the Hayman fire, largest in Colorado’s recent history in acreage, which denuded close to 100 square miles and coming within 1000 feet of the station. Temperatures at the site have run quite a bit higher since then, and I’m sure were very high the week of the fire (although the observers were wisely evacuated). That fire generated a spectacular orange supercell firestorm that I was watching warily from my home (and co-op station) 40 miles to the north.
Steve… If you want to do some dendro studies near my place, I have good records back to 1982 and there’s bristlecones not far from my home/coop site (Coal Creek Canyon). I also have an increment borer, and need to learn how to use it!

Figure 3 is damning for paleoclimatology. It shows three widely accepted techniques for interpreting tree ring wood as a proxy for temperature. It demonstrates that trees are useless as temperature proxies for anything other than qualitative impressions.

Reading any meaning into fractions of a degree centuries ago based on tree ring proxies is climate Rorschachism..

I think expert in tree physiology, wood anatomy and plant cell biology Prof. Rod Savidge sums it up well in his email-

“ClimateGate Email 1738
“However, there are bounds to dendrochronology, as there are to every field of investigation, and the discipline has spilled over way outside of those bounds, to the point of absurdity.”
“What troubles me even more than the inexactness attending chronological estimates is how much absolute nonsense — really nothing but imaginative speculation — about the environment of the past is being deduced from tree rings and published in dendrochronology journals.”

RHS: One question about the Cheesman USHCN station. How well situated is the site considered?
I believe what you are looking at in the overhead views is an out-of-service Stevenson screen. The ranger I talked to this July thought it was replaced by the MMTS in 2000. The current instrument is a few feet southeast at 39.220166, -105.278233. Sorry, I’ve been slow in posting a writeup of my visit. The site seems to have the normal anomalies in NOAA’s reporting of history: Their location reports would have put it into the water well out in the reservoir during one time period. I haven’t had time to try to shake it down. Would be really helpful if we could get access to the B44’s without an act of Congress.

I suspect the site has not actually been moved since its creation. Your remarks seem to me to be valid, but I don’t evaluate these things, I just take pictures. : > )

John W says:
September 11, 2012 at 10:05 am
Are you saying that it did not happen?
Not necessarily, just introducing some caution in interpreting proxies. Of course, when the proxies confirm one’s pet theory they are good, right? And when not, they are bad [or other effects corrupt the data], right?
———

Yes, I saw that in the debate with the Stanford study of Organic nutrition. Saying that Organics have the same nutritional value as non-organic foods.

chris y says:
September 11, 2012 at 1:07 pmFigure 3 is damning for paleoclimatology. It shows three widely accepted techniques for interpreting tree ring wood as a proxy for temperature. It demonstrates that trees are useless as temperature proxies for anything other than qualitative impressions.
Using the 18O isotope as the indicator is independent of the material being wood. The isotope method woks with any material containing oxygen: chalk, wood, ice, whatever. So [and that is the main point of the paper], the first graph should be fine.

Leif and Steven, you have to admit that tree rings as a temperature proxy are a fail. This has been known for decades. Steve Mc has spent his vacation showing the lunacy of tree rings as a temperature proxy. This he did in spades. Why would it show the LIA if it did not show a hockey stick? Your point is moot.
For supposedly learned men, you both seem rather obtuse sometimes.

David Ball says:
September 11, 2012 at 1:33 pmyou have to admit that tree rings as a temperature proxy are a fail. This has been known for decades.
Using the 18O isotope as the indicator is independent of the material being wood. The isotope method works with any material containing oxygen: chalk, wood, ice, whatever. So [and that is the main point of the paper], the first graph should be fine.

“Not necessarily, just introducing some caution in interpreting proxies. Of course, when the proxies confirm one’s pet theory they are good, right? And when not, they are bad [or other effects corrupt the data], right?”

I think that’s the whole point this brings up. What is the proxy really showing us? It’s flattish from end to end, using any of the measures from the trees.

I don’t envy the job of paleoclimatologists. But one thing is for sure, temperatures by these tree types don’t go spiking in the 20th century, or.. anywhere really. Seems they are happy to chug along whatever the “average” global temperature ranges.

Three rings at high latitudes follow the summer NAO (atmospheric pressure difference) rather than temperatures, see graph for 1700-1850http://www.vukcevic.talktalk.net/TreeRingsNAO.htm
ABSTRACT:
Summer climate in the North Atlantic-European sector possesses a
principal pattern of year-to-year variability that is the parallel
to the well-known North Atlantic Oscillation in winter. The summer
North Atlantic Oscillation (SNAO) is defined here as the first
empirical orthogonal function (EOF) of observed summertime
extratropical North Atlantic pressure at mean sea level…….
Reconstruction based on 7 tree ring chronologies in Norway
and the UK:
data: ftp://ftp.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/snao-folland2009.txt

Why did’nt they just saw through the legs of the plastic tables in Starbucks and count the rings? The results would have been just as relevant and the vandalism to Starbucks would reflect the vandalism to proper science

Jimmy Haigh says:
September 11, 2012 at 9:41 am
But why? Was there no Little Ice Age? Or is it because trees are just not good thermometers?
Several possibilities:
1) perhaps LIA was not global
2) perhaps trees no good for temperatures
3) perhaps solar activity was not a low as thought
Pick your poison.

But some indication of the MWP has been found in Bristlcone pines, and was even reported on -before it became heretical.

Never trust a conifer
The Deseret News – Jan 8, 1993http://news.google.com/newspapers?id=TwIrAAAAIBAJ&sjid=NZcFAAAAIBAJ&pg=1478,2721092&dq=medieval-warm-period&hl=en
An editorial from Scripps Howard News Service
Three-thousand years before Christ, the saplings of bristlecone pines poked through the earth and began recording what would become five millennia of climatic changes. In studying these ancient trees, University of Arizona scientists have figuratively laid the ax to today’s fashionable global warming theory.
To be sure, the tree rings tell of balmier eras, growing wider in conjunction with, for example, the Medieval Warm Period of 1100 to ‘1875 A.D. During this time, grapesburst forth In England and Vikings farmed in now-frigid Greenland: (Heck on chlorofluorocarbons, those Norsemen.) In contrast, researchers have detected no fatter outer rings that would inevitably announce the so-called greenhouse effect.
The findings of UA’s Laboratory of Tree Ring Research will hardly shake up most climatologists: Only one in six accepts the apocalyptic version of global warming. But pity true-believing environmentalists, the oft-mocked “tree huggers.” One of their major tenets is weaker than ever, thanks to the-perfidy of the pine.

She has seen in the North American trees the feathery but unmistakable signatures of the Medieval Warm Period, a era from 1100 to 1375 A.D. when, according to European writers of the time and other sources, the climate was so balmy that wine grapes flourished in Britain and the Vikings farmed the now-frozen expanse of Greenland; and the Little Ice Age, a stretch of abnormally frigid weather lasting roughly from 1450 to 1850. A Crucial Question

“We can now see that these were global climate phenomena, not regional temperature variations,” she said. “The question is, how did we get those warmer temperatures during pre-industrial times, and what can we learn from those conditions about what is going on today?”

The rest of that article is worth reading.

To anybody asking where is the LIA or hot 1930’s. Tree-rings aren’t great proxies for temperature. They’re not worthless, but relying on a small sample for any geographical area or time period, is almost worthless. Michael Mann’s hockey stick was front and centre in the warmist propaganda. His claims of difficulty and expense in obtaining samples is frankly absurd. Billions have been spent on global warming research and trillions are at stake in the global economy, yet they can’t send a few guys out with a simple tool costing at most $350 to do a basic task any carpenter, handyman or indeed anyone could do after a morning’s training.

vukcevic says:
September 11, 2012 at 2:23 pmThree rings at high latitudes follow the summer NAO (atmospheric pressure difference) rather than temperatures
You [and many others] missed the whole point of the paper: The 18O isotope method has nothing to do with the growth of tree rings, but with the temperature of the water that produced the water vapor that condensed to rain which watered the tree. http://en.wikipedia.org/wiki/Oxygen_isotope_ratio_cycle

“4) That even though the LIA was global it wasn’t evenly distributed throughout all locales, in other words, some places wouldn’t have had a temperature drop even if most places did.”

It’s important to remember that even during our current century-long warming, 1/3 of all temperature stations have recorded either no change, or a drop in temperatures. So it’s hardly unprecedented that a period of global warming would include many areas of the earth that do not experience warming, for whatever reasons. Another reason to suggest that “average global mean temperature” is a fairly meaningless statistic.

David Ross says:
September 11, 2012 at 2:54 pmTree-rings aren’t great proxies for temperature. They’re not worthless, but relying on a small sample for any geographical area or time period, is almost worthless.
Using the 18O isotope as the indicator is independent of the material being wood. The isotope method works with any material containing oxygen: chalk, wood, ice, whatever. So [and that is the main point of the paper], the first graph should be fine.

Leif Svalgaard says:
September 11, 2012 at 10:28 am
Don Keiller says:
September 11, 2012 at 10:13 am
But this work is only representative of one small location.
It cannot and does not have relevance/teleconnect to the global situation.
Yet people are falling all over each other to trumpet the relevance of this series. If it is not relevant, then why laud it?

For exactly the same reason as Mann, the IPCC, and alarmists everywhere trumpet the relevance of Bristle Cone Pines and “The ONE Tree” from Yamal as having Global significance.

Leif Svalgaard says-
“Using the 18O isotope as the indicator is independent of the material being wood. The isotope method woks with any material containing oxygen: chalk, wood, ice, whatever.”

Can you explain how the 18O isotope measurement (is it ratio or absolute amount) in tree wood can be used as a proxy for air temperature? I have seen descriptions for d18O wikipedia, but the interpretation seems to be very dependent on the substrate, biochemistry, precipitation and other interfering influences.

“While paleoclimatologists are attempting to update many important proxy records to the present, this is a costly, and labor-intensive activity, often requiring expensive field campaigns that involve traveling with heavy equipment to difficult-to-reach locations (such as high-elevation or remote polar sites). For historical reasons, many of the important records were obtained in the 1970s and 1980s and have yet to be updated.”

What a strange comment. According to Mann, the world hangs in the balance. Depending on what policies governments adopted, trillions of dollars are at stake, and don’t even get started on the humanitarian aspects. Multimillionaires traipse around the world, charging $100,000 speaking fees, to bloviate on our impending doom.

And yet Mann can’t access better information because taking a few core samples would break his budget.

chris y says:
September 11, 2012 at 3:18 pmCan you explain how the 18O isotope measurement (is it ratio or absolute amount) in tree wood can be used as a proxy for air temperature?
The principle is very simple: 18O is heavier than 16O, so a water molecule having an 18O atom instead of 16O is heavier than one with 16O. It therefore takes a higher temperature to evaporate that molecule into water vapor. The ratio between the number of 18O atoms to 16O atoms is therefore a measure of the temperature when the water evaporated. That vapor now goes into clouds and is perhaps moved around a bit, say within 1000 miles, before condensing into rain that falls down to water the tree [so the tree does sample a rather large area, not just a few feet around it]. If most of the water that the tree sucks up is surface water [and for bristlecones that is certainly the case as they grow just on top of the rocks and don’t have deep roots into a subsurface reservoir] the wood that forms will contain some of that recent 18O that is in the rain that just fell and we can thus estimate the temperature of the water that evaporated to form the clouds that gave the rain that watered the tree.

Using the 18O isotope as the indicator is independent of the material being wood. The isotope method works with any material containing oxygen: chalk, wood, ice, whatever. So [and that is the main point of the paper], the first graph should be fine.

Point taken.

My criticism rant was really addressed at Michael Mann’s use and abuse of tree rings. Just couldn’t help myself : )

I’m a scientific layman. But I’m familiar with Dansgaard’s method of measuring Oxygen-18 or deuterium (heavy water) in polar ice cores. Which I understand is the basis of ice core temperature proxies used by the IPCC. I wasn’t familiar with the notation “d18Oc”. I did a quick Google search of “d18Oc isotope” and got “carbonate oxygen isotope.” But no reference to ice cores. Is the above “d18Oc” isotope method related to, similar or the same as Dansgaard’s method?

Alex Avery says:
September 11, 2012 at 3:42 pmWait, but Leif, at what temp (altitude) was the water condensed? Is that always the same as the bristlecone pine? I’m confused.
It is the temperature where the water evaporated that is important, so most of it comes from the oceans or some warm and wet place, but the paper has details [go read it…].

For a quick summary, the article says that warmists find the fact that sceptics talk sensibly to be a threat to their world view which requires us to be wrong. So they invent a mythical “bogeyman” to explain to themselves how sensible people can be sceptics.

But the real problem them becomes how they can justify this “Bogeyman” … which is usually fossil fuel.

David Ross says:
September 11, 2012 at 3:55 pmBut no reference to ice cores. Is the above “d18Oc” isotope method related to, similar or the same as Dansgaard’s method?
It makes no difference if the 18O is stored in ice, wood, seashells, or calcite rocks. The method is fundamentally the same [the details will always differ a bit]. The ice, wood, etc are just archival mediums that are solid enough that the atoms don’t move after deposition.

David Ross says:
September 11, 2012 at 2:54 pm
yet they can’t send a few guys out with a simple tool costing at most $350 to do a basic task any carpenter, handyman or indeed anyone could do after a morning’s training.
===================================================================
Ohhhhhhhhhhhhhhhhhhhhhhhh !!!
I see a citizen’s brigade running around like the Surface Stations project !!!!

Here’s a video clip of a tree core being sampled. I wonder how many people it took to carry that core sampling tool to the location?

Here’s the only place I found that sells Increment Borers. They don’t give prices nor do they appear to sell online. On another website it stated that they were $300 and up.

I have an oak tree that’s is 56 inches in diameter and this website gives a basic method of determining tree age. According to this method the tree is 280 years old. Does that sound accurate? The tree isn’t in the forest and the site states that this is for determining trees growing in the forest. Which, I assume, a non-forest grown tree would grow at a faster rate and that would mean the age would actually be less.

Leif Svalgaard says:
September 11, 2012 at 3:02 pm
[…] So [and that is the main point of the paper], the first graph should be fine.

That all depends on whether or not the calibration of the ratios were consistent with the environmental variability of the collection site versus standardd assumptions used in other calibrations.

Some of the results of such isotopic studies for the Antarctic ice cores are suspect, because the assumptions used to formulate the calibrations failed to account for differing oceanic sources and varying seawater temperatures for the precipitation incorporated into the glacial ice.

Has anyone ever attempted to determine by experimentation the sources of the precipitation for this site, and did they determine to what extent those sources varied over the period under study?

I ran the numbers on the temperature/d18O conversion formula they used. It is very consistent with the formula one would use for mid-latitude, mid-continent scenario. The authors built their own formula based on the local temperature/local dO18 measurements but it turns out to be basically the same as other places in the world with similar conditions.

The formula changes depending on latitude, altitude and proximity to an ocean (something that climate scientists usually have no concept of based on the formula that has been used in other settings/climate science studies).

I happen to be a big believer in the d18O isotope as long as it is used properly. It is by far the best proxy there is.

It is the temperature where the water evaporated that is important, so most of it comes from the oceans or some warm and wet place, but the paper has details [go read it…].

Eh…that’s not really helpful for those of us who aren’t members of the AGU.

But you’re explanation at 3:53 pm helped clarify. As I understand it, they’re using the same method as that used to derive temperature proxies from polar ice cores, which should be independent of tree ring width or density.

The notation “d18Oc” threw me, but it’s just a typographical limitation of WordPress. The abstract, at the link provided, makes it clear we’re talking about the ratio of two isotopes oxygen-18 (heavy) and oxygen-16 (regular).

Leif Svalgaard wrote:

It makes no difference if the 18O is stored in ice, wood, seashells, or calcite rocks. The method is fundamentally the same [the details will always differ a bit]. The ice, wood, etc are just archival mediums that are solid enough that the atoms don’t move after deposition.

Got it.

On a bit of a side note, I perused your website and note your interest in sunspots, cosmic rays, etc. Would you not be more interested to see measurements of carbon isotope ratios taken from tree rings and compared with the temperature record?

Some of the results of such isotopic studies for the Antarctic ice cores are suspect, because the assumptions used to formulate the calibrations failed to account for differing oceanic sources…

But those problems are acknowledged by the ice-scientists together with problems with air bubbles migrating and not matching the date of the ice that entraps it. So they are not appropriate for yearly or probably decadal temperature variations.

I have only read the abstract, so I don’t know to what extent the authors of this paper have addressed the issue of resolution.

Regarding the wood incorperating O16 vs O18: I imagine if the trees were watered by summer rains from a sub-tropical jet they’d have more O18, but if they were watered by melting snowpack lingering above the roots, and the snowpack was delivered by a winter’s polar jet, you’d have less O18. If this were true than the amount of O18 would have little to do with the world’s temperature, and everything to do with the sourse of the precipitation.

Thanks. The location and number of reference temperatures used in the calibration segment seems to be quite important. Choosing temperature records within a 1000 mile radius could provide plenty of opportunities for picking a path to a desired result. Are there any standards set by paleo researchers to avoid cherry picking pitfalls?

Has the resulting 18O concentration measured in the wood been shown by laboratory experiment to accurately reflect the 18O concentration in the water supply?

There are many plants that operate/live at a temperature higher than the surrounding environment and one of them is the Delicious Monster Plant (with the big leaves and twisted thick stems that one often sees in offices). They are Arums. Some arums can maintain their growing fruit tips about 10 Deg F above the ambient air be mixing oils together. Just before a DMP flowers the pod rises rapidly in temperature after sunset and bursts open the following day with thousands of tiny flowers on what will become the delicious fruit.

Arum lilies that push through the snow in spring literally melt their way upwards. I believe it has always been assumed that plants are ‘cold blooded’ and that basically no one checked what their temperatures actually are. It does not surprise me at all that the hardiest trees are capable of changing their internal temperature, and recording it, maybe. This may apply to all trees that have a growth limited by temperature. Why not? Makes evolutionary sense. A common element would be oils and resins that can be stored and mixed to generate heat. Sounds a lot like pines to me!

David Ross says:
September 11, 2012 at 5:22 pm“but the paper has details [go read it…].”
Eh…that’s not really helpful for those of us who aren’t members of the AGU.
At the beginning of this thread Anthony has a link to the full paper.

There’s too much to read every comment in detail. I noticed a mention of a cold bias in the bore record. Could that be due to the weight of the tree tending to crush the inner layers of wood perhaps involving a process that removes water from the inner wood, shrinking the rings? In that case, density and isotope data together might describe the system pretty well. I wonder whether the density correction also corrected out the LIA signal. After shrinking the rings at age, maybe there is little temperature signal left.

This AGW psychosis does serve one good purpose and that is as a kind of Rorschach test. Just consider Sea-Ice minimum extents, temperature trends, hot days in July as the proxy ink-blots. If someone looks at these and always sees something creepy or fatalistic you might want to keep an eye on them. Normal people would do well to identify these kooks in their day-to-day lives, when you interview someone to hire as an employee, a babysitter, to shovel your driveway, to fix your car, be your doctor or pediatrician, etc. You can’t put a price tag on rationality and common sense and these kooks fail at both.

Leif Svalgaard says:
September 11, 2012 at 2:57 pmThe 18O isotope method has nothing to do with the growth of tree rings, but with the temperature of the water that produced the water vapor that condensed to rain which watered the tree.
Thanks. Stalactite rings would be a good proxy for a long term temperature records.
On unrelated matter and irrelevant to tree rings:
‘geomagnetic activity, lasts longer and is often stronger at night time’ (re: electric current induction in electricity grid) ?
Correct or wrong?

@- Blade says:
“This AGW psychosis does serve one good purpose and that is as a kind of Rorschach test. Just consider Sea-Ice minimum extents, temperature trends, hot days in July as the proxy ink-blots. If someone looks at these and always sees something creepy or fatalistic you might want to keep an eye on them. ”

And in like manner someone who looks at sea-ice minimum extents, temperature trends and hot days and does not suspect something beyond natural variation, you may want to send them for remedial classes in apprehending reality.

The trouble with the d18O measure of temperature is that it is usually a measure of regional sea surface temperature. That does not show much variation over the last few thousand years as indicated from the static sea level over this time.
The recent {last century} rise in sea level indicates that this stasis is no longer in operation.

vukcevic says:
September 12, 2012 at 12:07 am‘geomagnetic activity, lasts longer and is often stronger at night time’ (re: electric current induction in electricity grid) ? Correct or wrong?
Generally correct as GA is mostly due to release of energy stored in the geomagnetic tail that stretches out in the anti-sun direction, although the ‘electricity grid’ bit is a bit odd here.

And in like manner someone who looks at sea-ice minimum extents, temperature trends and hot days and does not suspect something beyond natural variation, you may want to send them for remedial classes in apprehending reality.

I offer some help.

People who apprehend reality know that sea-ice minimum extents, temperature trends and hot days are all observed to be within natural variability. So people who “suspect” otherwise need to seek help in case their delusions start to affect important parts of their lives.

According to the cosmic-ray hypothesis (i.e., solar activity shields the earth from cloud-causing cosmic rays) periods of low solar activity, such as the Little Ice Age, would have more clouds. Since clouds both reflect sunlight back into space and also produce rain, they produce colder and wetter climate at the same time.

If so, then Michael Mann’s tree-ring data missed the Little Ice Age because that period’s high-cosmic-ray induced climate change was colder and wetter than normal. And Michael Mann ignored the 1975-2000 tree ring data because that’s period’s low-cosmic-ray induced climate change was warmer and dryer than normal.

Thus tree rings may be the best metric whenever the goal is to examine that climate change not caused by variations in solar activity.

>Tree rings may be the best metric at all.
>…
>If so, then Michael Mann’s tree-ring data missed the Little Ice Age because that period’s high-cosmic-ray induced climate change was colder and wetter than normal.

This statement accepts that Michael Mann presented the result of his investigation, i.e. the results as shown in the data. This is not true. He did not ‘miss it’. When all the data he had available is included, it clearly indicates there was a LIA so he did what is called in mathematics ‘cheating’ (which is, believe or not, a technical term) and left out data that produced the LIA dip in temperatures. He then used multipliers for tree ring sets that were more to his liking, different multipliers for different data sets to such an extent that some trees counted more than 300 times the ‘weight’ of others. The result pleased him and his sponsors so it was (eventually) published as MBH98. It is wise to recall that the IPCC accepted the paper before it was published. This is both extraordinary and in breach of their own rules, casting some considerable doubt on their intentions.

His misrepresentation of the data does not undermine your argument, however. It would be helpful if you were to clearly separate anything to do with the Mann publications and what is generally considered ‘normal scientific work’. The cosmic ray hypothesis is still a work in progress and is receiving a lot of attention, which it deserves because the physics are sound and no one is suppressing the data and methods.

I seem to recall a paper discussed here on WUWT claiming that plants tend to maintain an internal temperature that varies less than their external environment.
****

I believe that’s the leaf temp that stays relatively constant (~70F?). Makes sense since the leaf is the evaporation “machine” that regulates the evaporation (and thus temp) by the size of the stomata openings. The wood and stems do not evaporate significantly and so are roughly at ambient temp.

I have an oak tree that’s is 56 inches in diameter and this website gives a basic method of determining tree age. According to this method the tree is 280 years old.
****

Offhand, it sounds in the ballpark. Where I grew up a Q. alba (white oak) in good soil nearby was about 90″ dia at breast height. Coring determined it was ~320 yrs old (that was 40 yrs ago). It’s still in good shape. The deceased Wye oak in MD was well over 10 ft dia & around 600 yrs old.

Good point, however there are good reasons as well to assume that trunks, which contain different types of resins as you go deeper into them, may be able to regulate the temperature to some extent, for example warming in spring to give that species a competitive advantage. The resins (which form amber) are very high energy compounds which is why pine wood has more heat in it than other trees (per dry kg). Resins are energetically expensive – why make them? Mixing oils or washing one oil over a stored resin can generate heat as it released stored energy at the beginning of the growing season. Given the environment in which the bristelcone pines grow, it is worth checking with a ‘treemometer’, to borrow a term!

>Regarding “warm blooded plants.” In New England, Skunk Cabbage blooms melt their way up through solid ice in swamps. I always wondered how the heck they knew it was spring.

The length of the daylight (a gene switches on). The heat is produced by mixing stored oils which also protect it from freezing. It is easy to check the temperature difference with a thin thermocouple probe.

How many cores would be required to provide a chronology acceptable to the dark side… er climatologists?

What standards for documentation would be observed?

What permission needs to be obtained.

These are irritating questions, but they need to be considered beforehand. Some of the oldest trees may be protected. Several years ago, I tried to get permission from the relevant forest service offices to take cores from a “preserve” – it was peremptorily denied, and I was threatened with a substantial fine. The ranger went on to ‘splain how I’d need to initiate an environmental impact study at my own expense, costs that could run into the multiple thousands, etc, etc. Universities and researchers harvest cores from this site routinely, publishing their studies online, so it helps to be “affiliated”. It seems to me that Steve McIntyre did request permission for his Starbucks expedition – and received it uneventfully, but I don’t think he was in a sanctuary.

Yes and no.
I’ve been pointing that for some years now.http://www.vukcevic.talktalk.net/CETsw.htm
– Yes, because the TSI doesn’t vary much and the N. Hemisphere gets most of it in summer and least in the winter, and yes the winters are that have the 300 year uptrend.
– No, because temperature natural variability is caused by geomagnetic activity, which lasts longer during the night, and the winter nights are much longer than the summer nights.
See you. :)

#############

Vuk I think you miss the point of my comment.

I am focusing on the structure of argumentation. Nothing else.

So for example, you will see people argue that more ice in the antartic is inconsistent with global warming when it is clearly not.

David Ball says:
September 11, 2012 at 1:33 pm (Edit)
Leif and Steven, you have to admit that tree rings as a temperature proxy are a fail. This has been known for decades. Steve Mc has spent his vacation showing the lunacy of tree rings as a temperature proxy. This he did in spades. Why would it show the LIA if it did not show a hockey stick? Your point is moot.
For supposedly learned men, you both seem rather obtuse sometimes.

###############

just WHO exactly do you think coined the term TREEMOMETER !!!

Now, to get to specifics about tree rings it would depend upon which measure you use

1. TRW
2. late wood max density
3. isotopes.

when I coined the term treemometer it was with respect to ring width. late wood max density and isotopes.. I keep a SKEPTICAL mind. which by definition is an OPEN MIND, not a mind that is made up.

For those who do not live in the US could someone please advise;
1. the distance between the pines used in this stufy and those used by Mann from Sheep Mountain, ie that gave him the great uptick in his hockey stick.?
2. Is there any significant difference in climate between the two sites ?

vukcevic says:
September 11, 2012 at 11:20 am
– No, because temperature natural variability is caused by geomagnetic activity,
===============
The earth sits in the beam of a massive particle accelerator, while scientists ignore the effects of the fluctuating magnets on beam density. Instead the are mesmerized by the glowing exciter at the center of the accelerator. Assuming that since the exciter is constant, the beam must be constant.

Scientists 150 years ago can be excused for missing the effects of the solar wind on climate. They didn’t know it existed. Modern science has no such excuse, except the are locked into the theories developed 150 years ago.

Contrary to CO2 theory the south pole is not warming. It is cooling as the south magnetic pole moves northward. The localized warming on the Antarctic peninsula is consistent with this northward movement.

None of the observed antarctic warming/cooling can be explained by CO2 theory. It is opposite to prediction. It is however entirely consistent with geomagnetic activity,

We see a similar effect in the arctic, where the north magnetic field is moving northward, leading to warming.

ferdberple says:
September 13, 2012 at 7:52 amNone of the observed antarctic warming/cooling can be explained by CO2 theory. It is opposite to prediction. It is however entirely consistent with geomagnetic activity,
Except that geomagnetic activity has not increased since the 1840s while temperature have…
So, NOT consistent.

I noticed that as well. I know Colorado is not California, but I can see Little Ice Age glaciers from my house here in the Eastern Sierra…the very glaciers that led Matthes to coin the term “Little Ice Age” in the first place.

I always get a kick out of tree-ring discussions….Here you can drive right up to the Bristlecone forest on the White Mountains, where the interpretive sign explains the dead trees above the treeline as from the medieval optimum, and the dead trees below the forest as from the little ice age ;)

I always get a kick out of tree-ring discussions….Here you can drive right up to the Bristlecone forest on the White Mountains, where the interpretive sign explains the dead trees above the treeline as from the medieval optimum, and the dead trees below the forest as from the little ice age ;)

This to me is pretty clear evidence of a MWP that was warmer than the present. If there are no comparably sized dead trees lie at a certain thermocline below modern treeline, it’s telling evidence of LIA too. If Leif believes that dO18 results are a viable demonstration of temperatures, I’d like to know what kind of chronology would be convincing evidence of these historical periods. The “proof” is at hand if someone wanted to core these relict trees above and below timberline and cross-date them with living trees. I strongly suspect this has been done somewhere, but I haven’t seen it. The signs you saw may just be stating the obvious without the scientific record to back it up, so the forest service offices might be the place to start. (Just thinking aloud, here, not assigning homework ; – )

Here in Colorado, too, many subfossil bristlecones lie in the tundra a few hundred vertical feet above present-day forests of the same species. The clear space between them, with nothing but scrub juniper and lichen-covered rocks, is the most eloquent demonstration I know of the hiatus between two growing periods. One core I took from a living b-c dates back to 1300. If the subfossils of comparable diameter (30″) died just a few hundred years ago, their cores would date to about 700 AD. Coring them would require a wide-diameter bit with a serrated tip for cutting, and a drill.

Bill Parsons says:
September 13, 2012 at 4:12 pmIf Leif believes that dO18 results are a viable demonstration of temperatures
That was not really my point. I wanted to say that if someone takes the paper as valid enough to refute AGW, then he also must accept that there was no LIA.

I don’t think I misunderstood, Leif. I saw the graph, saw your original comment. But I also saw a comment or two in support of using oxygen isotope analysis of tree rings to develop a temperature proxy. Stop me here before I go off on a wild hare, because, frankly, I’m getting interested in some of my old bristlecone cores all over again.

Do you know of any literature validating / describing this procedure for analysis of tree rings?

Bill Parsons says:
September 13, 2012 at 7:57 pmDo you know of any literature validating / describing this procedure for analysis of tree rings?
Not specifically for tree rings, but the procedure is very general and can be applied to anything that has oxygen in it which originated from water, so the temperature will be that of the evaporating water. not of the tree, of course, so there is still room for a lot of interpretation and caveats.